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More Effective Population Size Concepts

v Inbreeding effective population size ² the size of an ideal population with the same

probability of randomly sampled alleles being IBD as the real population

v Variance effective population size ² the size of an ideal population with the same

sampling variance in allele frequency as the real population

Inbreeding effective population size

v observed change in heterozygosity (IBD) over time can be used to estimate Ne

P IBD( ) = 12Ne

Nei =

12P IBD( )

Nei ! "

t2 ln Ht /H0( )

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Variance effective population size

v observed changes in allele frequencies over time can be used to estimate Ne

var !p( ) = pt"1qt"12Ne

Nev =

pq2xvar !p( )

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allele frequencies relative heterozygosity

1000 reps Ht=3 = 0.466187 Ht=4 = 0.463123 -0.00659416 75.82 Ht=0 = 0.50 Ht=4 = 0.463123 -0.0766154 26.10

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var !p( ) = 1n"1( )

!p"!p( )#2

! var(p) = 1n"1( )

p" p( )#2

1000 reps 0.502955 t4-3=0.000425 0.233094 0.00112872 103.26 0.502955 t4-0=0.002955 0.25 0.01844689 27.10

Random genetic drift in 107 Drosophila populations; 8 males, 8 females each generation

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Ht = 1! 12Ne

"

#$

%

&'

t

H0

( H0e!t2Ne